Why does my 1994 ford ranger start sometimes and not others it also stalls and won't start back up?

why does my 1994 ford ranger start sometimes and not others it also stalls and won't start back up but it does not happen all the time only once in a while. please help, i have no clue and not enough money to take it back into the shop!|||Open ther distributor and sparingly spray the inside of the cap with WD40. Cafefully wipe all this out with a clean rag. That should remove any moisture. Ford rangers will get a wet distributor in heavy rain or car washes. Make sure all the spark plug wires are clean, dry and tight. Do them one by one so they don't get mixed up.